Putting transparent image on curved surface with specific placement (UV)
You have to go to your node set up of your material for your blimp and add a Mix RGB node in which you will plug your transparent texture in the bottom color and the alpha of your texture to the factor of the Mix RGB node. Your color for the whole blimp should go to the upper color, finally you plug the Mix RGB node to your Diffuse node and then to your Material Output/Surface. *Don't Forget to unwrap the part of the blimp you want your transparent texture to be assigned.



p.s. if you want to have textures insted of colors you will have to create a second UV map, *don't forget to give your texture node the right UV map.



For more information I can recommend you this tutorial: *the blender version is quite old but the process is the same: 
https://www.youtube.com/watch?v=dnmovLzKU44